Re: [CAD_CAM_EDM_DRO] Newb question....

John Trevick wrote:

>
>Jon, can you clarify this for me. I am using your USC with steppers with
>encoders and EMC. If a stepper loses a step it does not recover? Or is
>what you said above not apply to the USC because it is more like a servo
>system?
>
>

If a stepper were to lose a step (or however much it takes to accumulate
more
axis error than the deadband value) at a low speed, it would recover so
well you
might never be aware of it. This could possibly happen due to the step
to direction
change timing not matching what the drive needed at a direction reversal.

If a stepper were to lose a step under heavy load at moderate to high speed,
the drive and motor could never recover until you slowed down or reduced
the load.
The motor would simply stall, and no amount of rapid step pulses would
get it
to pick up the pace as long as the load remains. As soon as the load or
speed was
reduced, then it could resume moving. Most likely, you would get a
following error
in this case before the motor could get out of the stalled condition.
If you want to
experiment with it, try reducing the motor current. With a Gecko drive,
you would
chage the resistor value, for instance. But, if the following error
limit is wide, or
the stall exists for only a small instant, then it would recover with
only that hesitation
in the motion. At any rate, even if EMC goes into E-stop, or the drives
fault out,
the position EMC is showing on the "actual position" display will still
be correct,
and it can resume operation without re-homing after the cause of the
stall is corrected.

Jon